Reversible acetylation of alpha-tubulin has been implicated in regulating microtubule stability and function. The distribution of acetylated alpha-tubulin is tightly controlled and stereotypic. Acetylated alpha-tubulin is most abundant in stable microtubules but is absent from dynamic cellular structures such as neuronal growth cones and the leading edges of fibroblasts. However, the enzymes responsible for regulating tubulin acetylation and deacetylation are not known. Here we report that a member of the histone deacetylase family, HDAC6, functions as a tubulin deacetylase. HDAC6 is localized exclusively in the cytoplasm, where it associates with microtubules and localizes with the microtubule motor complex containing p150(glued) (ref. 3). In vivo, the overexpression of HDAC6 leads to a global deacetylation of alpha-tubulin, whereas a decrease in HDAC6 increases alpha-tubulin acetylation. In vitro, purified HDAC6 potently deacetylates alpha-tubulin in assembled microtubules. Furthermore, overexpression of HDAC6 promotes chemotactic cell movement, supporting the idea that HDAC6-mediated deacetylation regulates microtubule-dependent cell motility. Our results show that HDAC6 is the tubulin deacetylase, and provide evidence that reversible acetylation regulates important biological processes beyond histone metabolism and gene transcription.

Molecular mechanisms associated with tumor metastasis remain poorly understood. Here we report that acquired expression of periostin by colon cancer cells greatly promoted metastatic development of colon tumors. Periostin is overexpressed in more than 80% of human colon cancers examined with highest expression in metastatic tumors. Periostin expression dramatically enhanced metastatic growth of colon cancer by both preventing stress-induced apoptosis in the cancer cells and augmenting endothelial cell survival to promote angiogenesis. At the molecular level, periostin activated the Akt/PKB signaling pathway through the alpha(v)beta(3) integrins to increase cellular survival. These data demonstrated that the survival-promoting function is crucial for periostin to promote tumor metastasis of colon cancer.

The late stages of human breast cancer development are poorly understood complex processes associated with the expression of genes by cancers that promote specific tumorigenic activities, such as angiogenesis. Here, we describe the identification of periostin as a mesenchyme-specific gene whose acquired expression by human breast cancers leads to a significant enhancement in tumor progression and angiogenesis. Undetectable in normal human breast tissues, periostin was found to be overexpressed by the vast majority of human primary breast cancers examined. Tumor cell lines engineered to overexpress periostin showed a phenotype of accelerated growth and angiogenesis as xenografts in immunocompromised animals. The underlying mechanism of periostin-mediated induction of angiogenesis was found to derive in part from the up-regulation of the vascular endothelial growth factor receptor Flk-1/KDR by endothelial cells through an integrin ␣ v ␤ 3 -focal adhesion kinase-mediated signaling pathway. These findings demonstrate the presence of a novel mechanism by which tumor angiogenesis is acquired with the expression of a mesenchyme-specific gene as a crucial step in late stages of tumorigenesis.

Tumor angiogenesis is of paramount importance in solid tumor development. Elevated serum levels of YKL-40, a secreted heparin-binding glycoprotein have been associated with a worse prognosis from a variety of advanced human cancers. Yet the role of YKL-40 activity in these cancers is still missing. Here, we have shown that ectopic expression of YKL-40 in MDA-MB-231 breast cancer cells and HCT-116 colon cancer cells led to larger tumor formation with an extensive angiogenic phenotype than did control cancer cells in mice. Affinity purified recombinant YKL-40 protein promoted vascular endothelial cell angiogenesis in vitro, the effects similar to the activities observed using MDA-MB-231 and HCT-116 cell conditioned medium after transfection with YKL-40. Further, YKL-40 was found to induce the coordination of membrane-bound receptor syndecan-1 and integrin αvβ3 and activate an intracellular signaling cascade including focal adhesion kinase and MAP kinase Erk1/2 in endothelial cells. Also, blockade of YKL-40 using siRNA gene knockdown suppressed tumor angiogenesis in vitro and in vivo. Immunohistochemical analysis of human breast cancer revealed a correlation between YKL-40 expression and blood vessel density. These findings provide novel insights into angiogenic activities and molecular mechanisms of YKL-40 in cancer development.

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Background: Engineered iron nanoparticles are being explored for the development of biomedical applications and many other industry purposes. However, to date little is known concerning the precise mechanisms of translocation of iron nanoparticles into targeted tissues and organs from blood circulation, as well as the underlying implications of potential harmful health effects in human.

GATA3, a transcription factor that regulates T lymphocyte differentiation and maturation, is exclusively expressed in early stage well differentiated breast cancers but not in advanced invasive cancers. However, little is understood regarding its activity and the mechanisms underlying this differential expression in cancers. Here, we employed GATA3-positive, non-invasive (MCF-7) and GATA3-negative, invasive (MDA-MB-231) breast cancer cells to define its role in the transformation between these two distinct phenotypes. Ectopic expression of GATA3 in MDA-MB-231 cells led to a cuboidal-like epithelial phenotype and reduced cell invasive activity. These cells also increased E-cadherin expression but decreased levels of vimentin, N-cadherin, and MMP-9. Further, MDA-MB-231 cells expressing GATA3 grew smaller primary tumors without metastasis compared with larger metastatic tumors derived from control MDA-MB-231 cells in xenografted mice. GATA3 was found to induce E-cadherin expression through binding GATA-like motifs located in the E-cadherin promoter. Blockade of GATA3 using small interfering RNA gene knockdown in MCF-7 cells triggered fibroblastic transformation and cell invasion, resulting in distant metastasis. Studies of human breast cancer showed that GATA3 expression correlated with elevated E-cadherin levels, ER expression, and long disease-free survival. These data suggest that GATA3 drives invasive breast cancer cells to undergo the reversal of epithelial-mesenchymal transition, leading to the suppression of cancer metastasis.GATA3 (GATA-binding protein 3) is a family member of zinc finger transcription factors (GATA1-GATA6) that bind with high affinity to the consensus DNA sites (T/A-GATA-A/G) (1, 2). GATA1, GATA2, and GATA3 are primarily expressed by hematopoietic cells, whereas GATA4, GATA5, and GATA6 are detectable in the cardiovascular system and endodermus-derived tissues, such as lung, liver, intestine, and pancreas (3). Functional studies of GATA3 in the lineage specification of hematopoietic cells have revealed that GATA3 mediates thymocyte maturation and is abundantly expressed by mature T lymphocytes (4, 5). Recently, it also has been found that GATA3 plays an essential role in the morphogenesis of embryonic mammary tissue. In the adult mammary gland, GATA3 acts on ductal epithelium to maintain the differentiation of luminal epithelial cells (6 -8); thereof, GATA3 is recognized as a key regulator of mammary tissue development and mammary gland formation.Over the past decade, considerable attention has been focused on the differential expression profile of GATA3 in different subtypes of human breast cancers. For instance, studies with differential gene expression techniques, including serial analysis of gene expression (available on the NCI, National Institutes of Health, Web site) and gene microarray have shown that GATA3 is highly expressed in estrogen receptor (ER) 2 -positive, early stage well differentiated breast cancers other than ER-negative, invasive cancers that are associated with worse ...

Accumulating evidence has indicated that expression levels of YKL-40, a secreted glycoprotein, were elevated in multiple advanced human cancers. Recently, we have identified an angiogenic role of YKL-40 in cancer development. However, blockade of the function of YKL-40, which implicates therapeutic value, has not been explored yet. Our current study sought to establish a monoclonal anti-YKL-40 antibody as a neutralizing antibody for the purpose of blocking tumor angiogenesis and metastasis. A mouse monoclonal anti-YKL-40 antibody (mAY) exhibited specific binding with recombinant YKL-40 and with YKL-40 secreted from osteoblastoma cells MG-63 and brain tumor cells U87. In the functional analysis, we found that mAY inhibited tube formation of microvascular endothelial cells in Matrigel induced by conditioned medium of MG-63 and U87 cells, as well as recombinant YKL-40. mAY also abolished YKL-40-induced activation of the membrane receptor VEGF receptor 2 (Flk-1/KDR) and intracellular signaling mitogen-activated protein (MAP) kinase extracellular signal-regulated kinase (Erk) 1 and Erk 2. In addition, mAY enhanced cell death response of U87 line to g-irradiation through decreased expression of pAKT and AKT and accordingly, abrogated angiogenesis induced by the conditioned medium of U87 cells in which YKL-40 levels were elevated by treatment with g-irradiation. Furthermore, treatment of xenografted tumor mice with mAY restrained tumor growth, angiogenesis, and progression. Taken together, this study has shown the therapeutic use for the mAY in treatment of tumor angiogenesis and metastasis. Mol Cancer Ther; 10(5); 742-51. Ó2011 AACR.